Map information regenerating device

Abstract: Disclosed is a map information regenerating device usable in a vehicle travel guiding apparatus, which is capable of freely revising a road map, i.e., adding, changing and deleting a road on the road map without changing data stored in a basic map-information storage but correlating change data with existing roads to assure the possibility of performing map-data processing such as course searching according to revised map data. The device is so constructed that a map information may be read-out from a map information storage and stored in a buffer memory wherein the data are revised in a specified procedure according to map change data read-out from an additionally used storage medium or/and obtained by using transmitting/receiving means.

Description: The present invention relates to a map information regenerating device. The Japanese laid open patent publication No. 4-50718 discloses a vehicle travel guiding apparatus which is capable of displaying a current location of a vehicle on a road map shown on a display screen on the basis of area-map data read from a map-information storage medium by successively determining two-dimensional coordinates of the vehicle by cumulative calculation of detected distances and a direction of its travelling. This apparatus is characterized in that a current location of the vehicle, which is indicated out of a road on the road map as a result of an accumulated error, can be corrected in such a procedure that a pattern of the vehicle's travel trace to the present location and a pattern of a selected road extracted from the map data are compared with each other for a match and then is aligned with the matched road. The Japanese laid open patent publication No. 62-133600 discloses another travel guiding apparatus for a vehicle, which is capable of setting a start point and a target point on a road map shown on a display screen and searching digital map data to find an optimal (e.g., the shortest) course therebetween for the purpose of guiding the vehicle. Map information to be used in the above-mentioned guiding apparatuses is generally stored as digitized data in a read only storage medium, e.g., CD-ROM. When the map is partly changed, for example, with addition of a new road, the storage medium in use shall be replaced with new revised one. To cope with any change made in the road map, it is proposed to use an additional read only memory (e.g., an IC card) for storing only revised map data, e.g., data relating to a new road or roads, in such a way that any changed information (e.g., a new road) may be read-out from the additional ROM and its image may be overlapped on a road map indicated on the. screen, which corresponds to the basic (not revised) data read from the data base stored in the road map-information storage. The drawbacks involved in the prior art devices are as follows: First, every time a road map is even partly changed, which may frequently occur, it is required to replace a full storage medium with new one. It is wasteful to use the storage medium in that way. In case when the additional ROM for storing changed data of the road map is used to read therefrom a necessary changed data of the road map and to display displaying the changed portion image by overlapping it on a basic road map displayed on a screen, which is based upon the road map data read-out from the map information (data base) storage medium, it is possible to add only a new road but impossible to change and/or delete any road shown on the screen. Particularly, overlaying an image of a newly laid-out road on the basic road map indicated on the screen may only synthesize two images without correlation between the changed data from a data correcting ROM and the basic road map data and, therefore, it can not indicate whether a newly added road meets and crosses with an existing road or merely crosses over the later without interconnection. In this case, it is also impossible to perform map-data processing such as pattern matching, optimal course searching and so on according to the revised map data. From the patent abstracts of Japan, Vol. 17, No. 239, P-1534 , which refer to the JP-A-4362683, a map-information generating device is known which includes a map-information storage medium in the form of CD-ROM and a road memory, in which roads not included in the road map data stored in the map-information storage medium can be stored by pressing a road memory switch of an operation device. Afterwords, the new road data stored in the road memory can be displayed as well as the road map date stored in the map-information storage medium, with different display colors being used for the new road map data and the existent road map data. From DE 34 00 602 A1 a navigation system for ships is known. The navigation system comprises a map-information storage memory for sea maps, a position determining means and a display. The navigation system is adapted to receive information referring to an up-dating of the sea map from an associated transmitter. In particular, the information received allows the sea map to be up-dated with respect to new ship wrecks, the provision of buoys, and the like. Since the navigation system only comprises the memory and the display, the up-dated information appears to be only superimposed over the sea map read from the memory without any revision of the map data itself. It is an object of the present invention to provide a map-information generating device capable of freely revising road map data, in particular capable of adding, changing, and deleting road data and correlating new or changed road map data with (old) map data read from a map-information memory of the map-information generating device. This object is achieved by the map-information generating device according to claim 1 and -alternatively- by the map-information generating device according to claim 2. Referring to claim 1, the provision of a buffer memory, a map-change information storage device, and a map-data processing means as specified in the claim allows the road map data contained in the map-information storage medium to be freely revised in accordance with map-change information stored in the map-change information storage medium. Accordingly, in the event that the road map data stored in the map-information storage medium are not up-to-date, any changes of the road map data needed to update the road map data can be effected without providing a complete new set of road map data or a new map-information storage medium. Since the (old) road map date can freely be revised by the map data processing means, there are no limitations with respect to the utilization of the changed road map data. In particular, any application apparatus using revised map-information from the map-information generating device receives the same information as if a new updated set of road map data or a complete, new, updated map-information storage medium were provided to the map-information generating device. Accordingly, further processing, such as course searching, can be effected without limitations. The same applies to the map-information generating device defined in claim 2. According to claim 2, a receiving means for receiving map-change information from an associated transmitting means is provided. With respect to map-change information prestored in a map-change information storage medium, such as an IC card memory, the provision of the receiving means has the major advantage that there is no need for acquiring a new IC card memory if the road map data are to be updated. Accordingly, as long as corresponding map-change information can be received from the transmitting means, the map-information generating device will always generate map-information which is up-to-date. BRIEF DESCRIPTION OF DRAWINGS Fig. 1 is a block construction diagram showing an example of a map information regenerating device embodying the present invention. Fig. 2 shows an example of digitized map information. Fig. 3 is a block construction diagram showing another example of a map information regenerating device embodying the present invention. In the drawings, 1 is a CD-ROM (compact disk read only memory), 2 is a buffer memory, 3 is an IC card memory, 4 is a data processing unit for revising map information, 5 is a control portion, 6 is a travel guiding apparatus for a vehicle, 7 is a transmitter, 8 is a receiver and 9 is a buffer memory. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, a preferred embodiment of the present invention will be described in detail as follows: As shown in Fig. 1, a map information regenerating device according to the present invention comprises: a compact-disk type read-only memory (CD-ROM) 1 as a map-data storage medium, wherein road map data digitized to express positions of link nodes and node-link connections for line segments (links) obtained by linear approximation of road components have been stored in advance; a buffer memory 2 for storing therein map data of an specified area, which are selectively read-out from the CD-ROM 1; an IC-card memory 3 as an only read storage medium for storing changed map information; a map data processing unit 4 for revising the map data stored in the buffer memory 2 by using the map change data read-out from the IC-card memory 3 in a specified procedure by using a specified processing program; and a control unit 5 controlling each portion of the device according to a specified control program. In Fig. 1, numeral 6 designates a travel guiding apparatus for a vehicle, which is generally applied for vehicle navigation and necessarily uses map information. The apparatus may be such that determines a current position of the vehicle on a specified area's road-map indicated on a display screen according to the map information read-out from the buffer memory 2 by detecting a vehicle's travel distance and a running direction and successively determining current position of the vehicle in a two-dimensional coordinate system by cumulative calculation or by electronic navigation using a GPS system. The vehicle travel guiding apparatus 6 is capable of correcting a current position of the vehicle, which may be indicated out of a road on the map as the result of cumulative calculation error in determining X- and Y-coordinates of the vehicle on the basis of its detected travel distance and running direction in such a way that a pattern of the vehicle travel trace obtained by retaining records of current position data is matched with the corresponding road pattern extracted according to the map information and then the trace is aligned to the identified road on the map indicated on the display screen. The vehicle travel guiding apparatus 6 is also capable of searching an optimal (e.g., the shortest) course from a start point and a target point preset on the road map indicated on the display screen according to the map information and guides the vehicle to follow the selected course. The operation of the map information regenerating device shown in Fig. 1 will be described as follows: When the vehicle travel guiding apparatus 6 receives an input requesting map information of a specified area, it gives an access instruction for obtaining a necessary map information to the control portion 5 which in turn reads the map data of the specified area from the CD-ROM 1 and stores the data in the buffer memory 2. The control portion 5 examines whether any change information for the specified map area is stored in the IC-card memory 3 or not, and, when the change information exists, reads said information therefrom and gives it to the map-data processing portion 4 for revising the map information, simultaneously driving a processing program to run. The data processing portion 4 reads the map data in the buffer memory 2, performs processing for revising the map data in a specified procedure according to the map change information and then returns the revised map information to the buffer memory 2. The control portion 5 informs the vehicle travel guiding apparatus that the required map data have been already prepared in the buffer memory 2, and then transfers the data from the buffer memory 2 to the vehicle travel guiding apparatus. In case when the IC card memory 3 does not contain any change information for the specified map area selectively read-out from the CD-ROM 1, the control portion 5 does not drive the map-data processing portion 4 and only transfers the map information from the buffer memory 2 to the vehicle travel guiding apparatus, previously providing the latter with an information that the required map data have been prepared in the buffer memory 2. Fig. 2 shows an example of map information which is composed of digitized data on nodal positions of links representing line segments approximating components of a road and connections of links with nodes. The digital map information consists of a node table containing position data (X- and Y-coordinates) of nodes (N1, N2, N3...) at both ends of each link (L1, L2, L3 ...), a link table containing serial numbers of both nodes of each link and a intersection (cross point) table containing serial numbers of nodes at each intersection (C1, C2, C3 ...) and serial numbers of links connected to each intersection. Table 1 shows contents of the node table, link table and intersection (cross point) table for map information shown in Fig. 2. Node Table Link Table Intersection Table N1 x1, y1 L1 N1 - N8 C1 N4 L2-L4-L5-L6 N2 x2, y2 L2 N2 - N4 C2 N8 L1-L3-L4-L7 N3 x3, y3 L3 N8 - N10 C3 N11 L6-L8-L9-L10 N4 x4, y4 L4 N4-N3-N7-N8 C4 N14 L7-L8-L11-L12 : : : : N17 x17, y17 L12 N14 - N17 Referring to Fig. 2, it will be described bellow how a new road shown by a dotted line is added to the area's map information read-out from the CD-ROM 1. In this case, the IC card memory 3 contains the following change map data written therein: (1) ADD [N17 + 1], 3, N1' (x1', y1'), N2' (x2', y2'), N3' (x3', y3') (2) MOD [L1], N2' - N8 (3) ADD [L12+1], 3, L1' N1-N2', L2' N2'-N3', L3' N1' -N2' (4) ADD [C4+1], 1, C1' N2' L1-L1' -L2' -L3' The data (1) mean that three new nodes N1', N2' and N3' must be added after the node N17 in the node table, and the data (2) mean that two nodes at both ends of the link 1 in the link table are to be changed by nodes N2' and N8 respectively. The data (3) mean that three new links L1', L2' and L3' must be added after the link L1 in the link table, and the data (4) mean that a new intersection C1' must be added after the intersection C4 in the intersection table. The map data processing portion 4 reads the map changing data written in the IC card memory 3 and revises the contents of the tables stored in the buffer memory 2 (for map information indicated in Fig. 2) according to the procedure (1) - (4). Table 2 is a table of changed map data. Node Table Link Table Intersection Table N1 x1, y1 L1 N2' - N8 C1 N4 L2-L4-L5-L6 N2 x2, y2 L2 N2 - N4 C2 N8 L1-L3-L4-L7 N3 x3, y3 L3 N8 - N10 C3 N11 L6-L8-L9-L10 N4 x4, y4 L4 N4-N3-N7-N8 C4 N14 L7-L8-L11-L12 : : C1'N2' L1-L1'-L2'-L3' : : N17 x17, y17 L12 N14 - N17 N1' x1', y1' L1' N1 - N2' N2' x2', y2' L2' N2' -N3' N3' x3', y3' L3' N1 - N2' Although the above-mentioned data are map change data to be added and modified by executing instructions ADD and MOD, there may be still other kinds of data to be deleted and moved according to basic procedures for executing instructions DEL [X] and MOV [X1], n, [X2]. According to the present invention, it is possible to easily make any complicated revision of the map information stored in CD-ROM1 by applying a combination of map data revising procedures, i.e., by adding, modifying, deleting and moving data relating to nodes, links and intersections, which are stored as map change information in the IC card memory 3. The present invention makes it possible to revise the map information by rewriting content of the data tables for digital map information instead of the conventional map image synthesizing method. Therefore, the device according to the present invention can judge whether a newly added road meets and intersects with a road on the basic map indicated on the display screen on the basis of the data and it enables the vehicle travel guiding apparatus 6 to carry out the above-mentioned kinds of map-data processing, i.e., correction of a current position of the vehicle by pattern matching method, searching of an optimal travel course for the vehicle and so on. In this embodiment, an IC card memory 3 of read-only memory type is used for supplying map change information but it may be an erasable programmable read-only memory (EP-ROM) which records can be rewritten to the latest map change information by using a terminal at a supplier of map information. Referring to Fig. 3, there is another embodiment of the present invention, which is a map information regenerating device not provided with any storage medium for map change information such as IC card memory and having a receiver 8 for receiving radio waves (or light signals) of map change information from a broadcasting station or a transmitting device installed along a road: the map change information received by the radio receiver under the control of a control portion 5 is stored in a buffer memory 9 and is used for revising a map information read-out from a storage CD-ROM 1 in the same way as described above. Thus constructed device can always get the latest map change information, being therefore free from the necessity of acquiring an IC card memory containing map change information at each time map is revised. In the device, it is also possible to add real-time traffic information (e.g., an average running speed and time required for passing a block between nodes N8 and N2' shown in Fig. 2) to the map information transmitted from the transmitter 7 so that a suitable travel course may be selected on the map indicated on a display screen of the vehicle guiding apparatus according to the real-time traffic service information. As is apparent from the foregoing, the map information regenerating device according to the present invention, which is provided with an additional storage medium usable for revising map information, is capable of freely rewriting content of a data table, which was read-out from a data-base storage for map information and stored in a buffer memory, according to a specified procedure for revising the map data by using the map change information read-out from the additional storage medium without changing the data base. The device is also capable of judging whether a newly added road meet and intersects with any existing road on the main map or not on the basis of the revised map data. The map information regenerating device according to the present invention, which, instead of an additional storage for map change information, is provided with transmitting-receiving means for receiving map change information transmitted from a fixed station. Accordingly, the device is capable of always obtaining the latest map change information from the station, eliminating thereby the necessity of replacing the additional storage of map change information with new one every time the map is revised.

Claims: Map information generating device comprising: a map information storage medium (1) for pre-stored digital map information comprising road map data expressing link nodes and node-link connections for links corresponding to line segments which approximate road components; a buffer memory (2) for storing map information for a specified area read from the map information storage medium (1); a map-change information storage medium (3) for storing map-change information specifying how the map information should be changed; a map-data processing means (4) for revising the map information stored in the buffer memory (2) according to map-change information read from the map-change information storage medium (3), the map-data processing means (4) being adapted to change and/or delete road map data read from the map-information memory (1) and to correlate added new road map data and/or changed road map data with road map data read from the map-information memory (1); a control means (5) for controlling the map-information storage medium (1), the map-change information storage medium (3), the buffer memory (2), the map data processing means (4) on request of an associated application apparatus (6) to effect the revision of the map information stored in the buffer memory (2) and for transmitting revised map information from the buffer memory (2) to the application apparatus (6). Map information generating device comprising: a map information storage medium (1) for pre-stored digital map information comprising road map data expressing link nodes and node-link connections for links corresponding to line segments which approximate road components; a buffer memory (2) for storing map information for a specified area read from the map information storage medium (1); a receiving means (8) for receiving map-change information from an associated transmitting means (7), said map-change information specifying how the map information should be changed; a map-data processing means (4) for revising the map information stored in the buffer memory (2) according to map-change information received by the receiving means (8), the map-data processing means (4) being adapted to change and/or delete road map data read from the map-information memory (1) and to correlate added new road map data and/or changed road map data with road map data read from the map-information memory (1); a control means (5) for controlling the map-information storage medium (1), the map-change information storage medium (3), the buffer memory (2), the map data processing means (4) on request of an associated application apparatus (6) to effect the revision of the map information stored in the buffer memory (2) and for transmitting revised map information from the buffer memory (2) to the application apparatus (6). Map information generating device according to claim 2, further comprising a further buffer memory (9) for storing map-change information received by said receiving means (8), said further buffer memory (9) being controlled by said controlled means (5) to effect the revision of the map information stored in the buffer memory (2). Combination of a travel guiding apparatus (6) for a vehicle and of a map information generating device (1, 2, 3, 4, 5; 1, 2, 4, 5, 8, 9) according to any of the preceding claims, the travel guiding apparatus being adapted to effect the travel guiding on the basis of revised map information received from said map information generating device. Vehicle equipped with a map information generating device (1, 2, 3, 4, 5; 1, 2, 4, 5, 8, 9) according to any of claims 1 to 3 and with an associated application apparatus (6) adapted to use revised map information received from said map information generating device. Vehicle according to claim 5, said application apparatus being a travel guiding apparatus (6).

Inventors: MASAHIRO OHOMORI, MASAYUKI ARAI, TAKESHI IMAI, MASAHIRO, OHOMORI, MASAYUKI, ARAI, TAKESHI, IMAI, MASAHIRO, OHOMORI, C/O KABUSHIKI KAISHA HONDA, MASAYUKI, ARAI, C/O KABUSHIKI KAISHA HONDA, TAKESHI, IMAI, C/O KABUSHIKI KAISHA HONDA
Applicants: HONDA MOTOR CO LTD, HONDA GIKEN KOGYO KABUSHIKI KAISHA
Application year: 1994
Main classification: G08G1
IPC codes: G01C21, G09B29, G08G1